Question: 7 markers cost $12.46. Which equation would help determine the cost of 5 markers?
Answer: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 7 markers. We want to know the cost of 5 markers. We can write the numbers of markers as a proportion: $\dfrac{7}{5}$ We know 7 markers costs $12.46. We can let $x$ represent the unknown cost of 5 markers. The proportion of these costs can be expressed as: $\dfrac{\$12.46}{x}$ The cost changes along with the number of markers purchased, and so the two proportions are equivalent. $\dfrac{7}{5} = \dfrac{\$12.46}{x}$